This invention relates to disk cartridges for use with a removable media disk drive. More particularly, the invention relates to an apparatus for retaining a shutter in a closed position when the cartridge is not in use.
Cartridge based tape and disk data storage devices for storing digital electronic information have been in use in the computer industry for several decades. Removable disk cartridges typically comprise an outer casing or shell that houses a disk-shaped magnetic, magneto-optical or optical storage medium upon which information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. Magnetic disk media can be either rigid or flexible and are mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a spindle motor in the drive engages the disk hub in order to rotate the disk within the cartridge at a given speed. The outer shell of the cartridge typically has a media access opening near one edge to provide the recording heads of the drive with access to the disk. A shutter or door mechanism is provided to cover the head access opening when the cartridge is not in use to prevent dust or other contaminants from entering the cartridge and settling on the recording surface of the disk.
When a disk cartridge is inserted into a disk drive, an arm engages the shutter and slides it toward the open position. However, when the disk cartridge is outside of a disk drive, the shutter must be kept in the closed position. Commonly, a spring is encased within the cartridge shell and provides a bias to the shutter toward the closed position. As a result, as the cartridge is ejected from the drive, the arm disengages from the shutter and the spring bias returns the shutter to the closed position. Although the spring generally achieves works, the spring has several drawbacks. For example, the spring adds complexity to the construction of the disk cartridge and, additionally, occupies valuable space within the cartridge shell. Accordingly, if the spring were not present in the cartridge the space would be available for media, allowing a smaller, less complex cartridge.
A prior art cartridge is disclosed in U.S. Pat. No. 4,517,617 (Tsuji). The Tsuji patent is generally directed to a disk cassette that contains a flexible magnetic disk having a center core (i.e., a hub) and an apparatus for reading and recording information on the flexible magnetic disk. The disk cassette comprises a flexible disk attached to a hub. The disk and hub assembly are sandwiched between an upper cover and a lower cover. To constrain the movement of the flexible disk within the cover, the hub has a center hollow which mates with a projection from the upper cover of the cassette. The shutter moves laterally across the faces of the disk cartridge exposing or covering a disk access opening.
The above disk and drive arrangements present a variety of drawbacks when applied to disk and cartridge systems of smaller physical dimensions. To reduce the overall dimensions of the drive and disk cassette, drawbacks of the prior art disk cassettes and removable media drives must be overcome.